Fractionation of shale oil by elution chromatography



United States Patent FRACTIONATION OF SHALE OIL BY ELUTION CHROMATOGRAPHY Robert G. Capell, Clarence Karr, Jr., and William D. Weatherford, Jr., Pittsburgh, Pa., assignors to Gulf Research & Development Company, Pittsburgh, Pa., a corporation of Delaware No Drawing. Application January 28, 1953, Serial No. 333,834

6 Claims. (Cl. 196-147) This invention relates to the fractionation of oils derived from oil shale and more particularly to a method of separating shale oil by chromatographic fractionation into fractions containing nitrogen and sulfur and fractions substantially free of nitrogen and sulfur.

Crude oils derived from oil shale offer a promising :source of hydrocarbon fuels and lubricants and valuable organic compounds. However, the separation of crude .shale oils into usable fractions presents serious problerns which are not met in the refining of crude petroleum .oil. These problems arise because of the high nitrogen and olefin content of shale oils and the high sulfur con- .tent of most shale oils. Because many of the nitrogen, olefin and sulfur compounds of the crude shale oil boil in the same range as the desired fractions, it is diflicult or impossible by conventional distillation alone to obtain salable fuel or lubricant fractions which are satisfaci'torily free of objectionable compounds. The presence of nitrogen in the various fuel and lubricant fractions presents a serious problem in that the nitrogen compounds give the fractions very poor color stability. Shale oil naphthas obtained by distillation turn black after a short time and are thus undesirable for com- ;mercial use. Furthermore, nitrogen compounds in the shale oil distillates are cracking catalyst poisons and prevent the desirable application of catalytic cracking to :shale oil and its distillate fractions. The presence of sulfur compounds in the Various shale oil fractions presents the numerous disadvantages which are well known .in connection with petroleum oil distillates, these disadvantages including unpleasant odor, corrosivity, and catalyst poisoning.

We have discovered that a shale oil of high nitrogen .Jand sulfur content can be separated into a fraction substantially free of nitrogen and low in sulfur compounds .and fractions rich in nitrogen and sulfur by subjecting 1such oil to elution chromatography, as more fully described hereinafter, using an alumina-type adsorbent and limiting the amount of charge to a specified maximum .charge to adsorbent ratio.

The process of the present invention makes it possible to fractionate shale oil, in-

cluding total crude shale oil and fractions thereof, of lhigh nitrogen content, i. e. at least about 0.2% by weight and in many cases more than 1% by weight, which is undiluted or only moderately diluted into usable fractions whereby all or most of the nitrogen and sulfur compounds are separated from a large portion of the shale oil. This result is obtained by chromatographic fractionation of the shale oil whereby separation is made mainly on the basis of molecular types rather than mainly on the basis of molecular weight as in conventional distillation.

Our process in general comprises introducing into contact with a bed of alumina-type adsorbent material a liquid comprising at least about 25 volume percent of a shale oil containing substantial amounts of sulfur and 2 nitrogen compounds in an amount which penetrates no inore than about percent of the length of the adsorbent bed. I The adsorbent bed is then eluted with a weak eluant such as a parafiinic liquid and an eluate of low sul; fur and low nitrogen content is recovered from the bed. Advantageously, the bed, after the introduction of the shale oil charge, is eluted with a series of eluant liq} uids of successively stronger elutive powers. Each eluant liquid removes a portion ofthe shale oil from the adsorbent bed, the first eluant removing the least strong ly adsorbed components of shale oil charge, and each of the subsequent eluants removing components which are successively more strongly adsorbed. Each eluate is collected as it emerges from the bed either as one fraction or in a number of successively collected portions.

The separation of mixtures by elution chromatography in accordance with our invention is influenced by a number of factors, including the type of adsorbent material employed, the type and volume of eluant liquids employed, the volume ratio of charge to adsorbent, and the temperature of the eluant liquids.

The character of the adsorbent material employed in our process is of great importance since the ability to achieve a separation between different types of molecules will depend upon the different degrees of adsorption of the molecules on the particular adsorbent.

Because different adsorbent materials vary greatly in their adsorptive aflinity for various types of molecules, it has been found that the fact that a particular adsorbent material has the proper relationship of adsorptive affinities with respect to the ditferent components of a particular oil or other material to be treated, offers no basis for predicting that the same adsorbent material will have a satisfactory adsorptive ailinity for the different constituents of a different starting material. In the fractionation of shale oil it is essential to use an adsorbent material which has the proper relationship of adsorptive affinity for different hydrocarbon compounds and for nitrogen and sulfur compounds. The fractionation of shale oil has been attempted with adsorbents other than those employed in our process but the results are unsatisfactory in a very important respect. Thus, U. S. Patent 2,606,143 describes fractionating shale oil into two fractions using a synthetic magnesium silicate adsorbent. One fraction had a relatively low nitrogen content and the other was rich in nitrogen. Both fractions contained about the same high percentage of sulfur; no separation of sulfur compounds was achieved. These results show the unsatisfactory nature of magnesium silicate as an adsorbent for chromatographic fractionation of shale oil containing nitrogen and sulfur, since it is incapable of producing a low-sulfur fraction.

We have discovered that the use of aluminum-type adsorbents makes possible the separation of shale oil into hydrocarbon fractions, and fractions containing sulfur and nitrogen compounds. The adsorbent employed in our process can be an activated alumina which is substantially pure alumina, or one which consists predominantly of alumina, or it can be activated bauxite (natural alumina). The adsorbent material is preferably used in a granular form which is freely permeable to liquid. Excellent results are obtained with particle sizes of from about 20 to 200 mesh. The adsorbent material is preferably disposed in an elongated vertical column. It is activated before use as by heating to an elevated temperature for several hours. The temperature of activation is not critical but we have found that temperatures between about 250 and 1400 F. and preferably between about 400? and 800 F. give good results.

The maximumratio of charge to adsorbent is also of great importance in our process. If an excessive volume of charge is introduced to the adsorbent column, the fractionation will begin as a percolation process rather than elution chromatography, and it will be difficult to obtainafraction.which is substantially colorless, substan fti'all-y free ofini'trogen compoundsand low'insulfur .con fen. asis obtainable by ourprocessi To avoidmere percolat'io'n of any of the oil, itis necessary that the, amount of 'oil chargedbesubstantially less than the amount necessary to penetrate the entire bed. When the charging of the oil is terminated and the introduction of the first eluant is begun, there must still be a portion of the bed that is unpenetratecl by the charge oil. Operating in this way, theinefficient technique of percolation is avoided.

The maximum ratio of charge to adsorbent Which is i of great importance in our process can conveniently be expressed as the extent to which the charge oil penetrates the adsorbent bed. In the process of our invention the charge mixture comprising shale oil is introduced to the adsorbent bed at either extremity thereof in an amount which penetrates no more than about 90 percent of the length of the adsorbent bed. There'is nolower limit for theamount of oil that can be charged insofar as obtaining sharp fractions is concerned. However, to use the capacity of the column most efiiciently, the amount should not be too small. In general, it can be said that the amount of oil charged should be that which will penetrate from about to about 90 percent of the adsorbent bed. It will be understood, however, that the extent of penetration within this range adapted to accomplish desirable fractionation will vary depending upon such factors the specific composition of the shale oil charge, the particular adsorbent used, and the equipment employed. Accordingly, in many cases the process should be carried out in such a manner that the charge oil penetrates substantially less than 90 percent of the adsorbent bed.

As indicated above, fractionation by the elution chromatography process of our invention involves the technique of adsorbing a fluid mixture in an adsorbent bed and then eluting the adsorbent bed with an eluant liquid or with a series of eluant liquids of successively greater elutive powers. In this way, components of the fluid mixture which are weakly held by the adsorbent bed are re-' moved from the bed in the first elution stage by a weak eluant liquid and more strongly held substances are eluted in the subsequent stages by successively stronger eluant liquids. v 7 Although in our process, it is preferred to employ a series of eluant liquids for producing a plurality of fractions of the'shale oil charge, it is also possible in accordance with the invention to use only a single eluant, preferably of weak eluting power, to remove a first fraction of the charge, and remove the remaining portion of the charge from the adsorbent bed by othertechniques.

A general principle that can be followed in selecting a series of eluants for chromatographic fractionation is that eluting power increases with polarity. Thus; nonpolar solvents such asparaflinic liquids are weak eluants and can advantageously be used as the first of a series of eluants in the chromatographic fractionation of shale oil. A parafiinic liquid of the naphtha boiling point range such as pentane'has such Weak eluting power that it will not desorb from the bed in a reasonable length of time therelatively strongly adsorbed substances such as sulfur and nitrogen compounds and substances of strong color. Consequently, it is possible with such a weak eluant to recover a first fraction from the adsorbent bed "which is substantially colorless and substantially free of a chromatographic fractionation as a displacer liquid to displace all remaining adsorbed substances from the bed.

in general the eluting power of a solvent increases with temperature. Consequently, a parafiinic weak eluant can be used as a moderate eluant by increasing its temperature',' o'r'a moderate eluant can be used as a strong eluant by increasing its temperature. pltis' possible to use the same eluant liquid for two or more elution stages by introducing it to the adsorbent bed at successively higher temperatures for the successive eluation stages. We have observed that a mixture of eluants having dif ferent eluting powers tends to have the eluting power of the strongest eluant and the elutive power of a weak or moderate eluant is greatly increased by the admixture of even very minor amounts of a strong eluant. For the efiicient recovery of Weakly adsorbed components of the shale oil such as hydrocarbons Without the inclusion of substantial amounts of the more strongly adsorbed nitrogen and sulfur compounds, it is important that the first eluant employed be a weak eluant which is substantially uncontaminated by any stronger eluant which would cause the elution'of undesired substances. The mixing of two more eluants having about the same order of eluting powers is usually not objectionable but the inclusion of even a very small quantity, e. g., 0.5 percent, of a strong eluant can form a mixture having a much stronger elutive power than .the major constituents of weak eluting power. This principle governs the purity of eluants that can be used for eluting the first fractions from the adsorbent bed. Thus, to obtain a weak eluant fraction of the shale oil which" is substantially colorless and substantially free of nitrogen and sulfur, it is essential that the first eluant be a weak eluant such as a parafi'inic solvent which contains no appreciable quantity of strong eluants such as aromatics, olefins, or polar compounds. p

The described effect of mixing a strong eluant with a weak eluant has the advantage of making it possible to employ as the moderate or strong eluant, mixtures which are predominantly relatively inexpensive paraffins and which contain only minor amounts, suflicient to give the desired eluting power, of more expensive eluants such as aromatics or polar solvents.

It should be clear from the foregoing discussion that in a cyclic process in accordance with our invention it is important to recover the eluants from the product fractions substantially uncontaminated with liquids of a higher order of eluting power before again using them as eluants in another cycle.

The importance in our process of using first stage eluants which are unmixed with strong eluants offers a partial explanation of the previously mentioned important element of the process, the maximum charge to adsorbent ratio. Thus, if the volume of charge introduced to the adsorbent bed before elution is begun exceeds the capacity of the bed, the charge in the bed will be eluted by the portion of charge which exceeds the capacity 'of the bed. Since the shale oil charge contains olefins, aromatics, and polar compounds which are moderate or strong eluants, the bed will be eluted by such moderate'or strong eluants in. the excessive quantityof charge. Since it is essential in our process that the bed he eluted with a series of eluants of successively increasing eluting powers, an elution of the bed by a portion of the charge itself before the first stage elution with a weak eluant would make it impossible to obtain the proper fractionation of the charge. in addition, poor recovery of weakly adsorbed substances would result from elution with a portion of the charge itself since these substances would be distributed throughout the bed owing to their presence in the entering charge.

The volume of eluant employed in each elution stage depends upon the desired degree of separation but is preferably about one to ten times the volume of the charge liquid. Much larger volumes of eluant can be emgamers *ployed but without improving the fractionation to any important degree. t If desired, a pressure differential can be imposed across the adsorbent bed either by applying pressure at the liquid inlet end of the bed or vacuum at the liquid outlet end of the bed. The efiect of such pressure differential is to increase the rate of flow of fluids through the bed.

It is possible in our process to separate a shale oil into a small number of fractions by recovering the entire amount of liquid eluted by an eluant as a single fraction. However, it is often preferred to take advantage of the differences in adsorbability of the constituents of the shale oil and collect the liquid issuing from the adsorbent bed in each elution stage in a number of portions. Because of their diiferences in adsorbability, certain types of compounds will emerge from the column first and other types will follow successively depending upon their strength of adsorbability. If proper cuts are made of the emerging liquid in this manner, it is possible to collect fractions consisting substantially of single types of petroleum compounds. The technique of collecting a fraction in several portions can be applied to any of the elution stages of our process and is a particularly valuable technique in fractionating shale oil for the recovery of valuable chemical compounds, such as olefins, aromatics, sulfur compounds or nitrogen compounds.

The fractionation process of our invention can be readily adapted to continuous or cyclic operation. In such a case, following the final elution with a strong eluant the adsorbent bed is purged of the strong eluant to prepare for the next cycle. It is possible to remove certain final stage eluants from the bed simply by Washing the bed with the first stage eluant for the next cycle. However, other final stage eluants must be removed in stages. Thus, for example, in a process employing n-pentane, benzene, and ethanol as the first, second, and third stage eluants respectively, it is impossible or impracticable to remove completely the ethanol remaining in the bed after the final elution by merely purging the bed with cold pentane. A suitable procedure is to wash the bed with benzene after the ethanol elution to remove the ethanol and then with pentane to remove the benzene before commencing the next fractionation cycle.

At the start of our fractionation process, the adsorbent bed can be either dry or wet but it is preferred to prewet the bed with the first stage eluant or with a weaker eiuant before introducing the shale oil to be fractionated. Prewetting is desirable for several reasons. in a cyclic process it assists in removing from the bed the last traces of the final stage eluant of the previous fractionation cycle. Prewetting also causes the shale oil charge to penetrate more readily the adsorbent bed and reduces chain neling in the bed. Still further, prewetting reduces or eliminates the heat of Wetting when the charge oil is introduced to the bed.

Shale oil has a high olefin content and, therefore, if the oil is overheated in the adsorbent bed, polymerization of the olefins with consequent formation of contaminating deposits on the absorbent bed can occur. The heat evolved on contacting a shale oil with a dry adsorbent bed can raise the temperature of particles of oil in contact with the adsorbent sufliciently to cause the undesirable polymerization of olefins, and therefore it is preferred to avoid introducing the charge to a dry bed.

In the continuous operation of our process, a plurality of adsorbent beds can be employed so that the charge oil can be introduced to one or another of the beds at all times while the other beds are undergoing elution or purging. Small quantities of materials may be unremovable from the bed by the usual eluting solvents and in such cases the bed can at intervals be subjected to regeneration such as by burning to remove accumulated carbonaceous deposits. a

' Although the ability to fractionate total crude shale 6 oil in a primary fractionation is particularly advantageous, our process can also be applied to the fractionation of various distillate or residue fractions of shale oil which are undiluted or only moderately diluted. With all such charges the valuable characteristic of producing a fraction substantially free of nitrogen and low in sulfur t is shown by our process. In accordance with our process,

the crude shale oil or fraction thereof charged to the adsorbent bed is diluted with no more than about 3 volumes of a low viscosity diluent or, in other words, the charge mixture comprises at least about 25 volume percent shale oil. The advantage of this novel feature of our process lies in the fact that the capacity of the adsorbent bed is most efliciently employed in that a large portion of the bed capacity is applied to fractionating shale oil rather than to the fractionation of a large quantity of a diluent liquid.

Because of the high viscosity of many crude shale oils and heavy fractions of such oils, it may be desirable or necessary to dilute the shale oil to some extent so that it will pass readily through the adsorbent bed. The diluent can in general be any solvent for the shale oil which is not so strongly absorbed in the adbsorbent bed as to inactivate the bed for fractionating the shale oil. Suitable diluents include liquids such as hydrocarbons of the naphtha, kerosene, gas oil or fuel oil ranges. Paraffinic hydrocarbons such as n-pentane or petroleum other are particularly suitable. It is also possible to dilute a high viscosity shale oil with a lighter crude shale oil or with a light shale oil distillate if desired. Still another possibility is the use of a low viscosity product of our process as the diluent. The amount of diluent required is, of course, merely the amount needed to cause the charge oil to pass readily through the adsorbent bed and in accordance with our process the liquid mixture charged to the adsorbent bed will comprise at least about 25 volume percent shale oil. With most crude shale oils a dilution with an equal volume of a diluent such as n-pentane or petroleum ether is adequate.

The following examples illustrate the results obtainable in fractionating a crude shale oil by the process of our invention. The crude shale oil fractionated by the procedure of the examples was a heavy, thixotropic, black, high boiling point liquid which had a high pour point, a high asphaltic content, a nitrogen content of 1.7 per cent by weight and a sulfur content of 0.67 percent by weight.

EXAMPLE I The crude shale oil diluted with about an equal volume of cyclohexane (about 6 grams of shale oil and about 10 ml. of cyclohexane) was introduced at the top of a two foot column containing about 70 ml. of 200 mesh activated alumina. The charge penetrated about 35 percent of the column. Immediately after the introduction of the entire shale oil charge, the column was eluted by introducing at the top of the column about ml. of n-pentane. The entire amount of liquid eluated in this stage was recovered as a single fraction. Following elution with n pentane, the column was eluted successively with 130 ml. portions of benzene and a solution of 25 volume percent ethanol in benzene. In each elution stage the entire eluate solution was collected as a single fraction. The fractions of the charge were then recovered from their eluate solutions by room temperature evaporation under a ventilating hood. In each stage of the chromatographic fractionation, the liquids were passed through the adsorbent column by gravity flow and no channeling difliculties were encountered. The fractionation was carried out at room temperature or about 77 F. The results of this fractionation in terms of characteristics and yields of the fractions obtained are given in Table I below. i it t t t v a 1 z Wt. N. Pen; veer-2:. Fractlon 1' Eluant Description Ber- Per-. cent t .8, cent of 11 x cent cent Total "Per Total' :.-.N.":ccnt r, S'.-

n-Pentano;.. Oolorlessthixotropicoil, 44.6 0.00 40.00. 0.18v 121). 1 .1 f g pleasant odor, ,blue I fluorescence. r Benzene. Brown-black semisolid 31.3 1.80- 33.1 1.28, 59.8

musty odor, no fluo- I rescence. 3 25 Vol. percent etha- Brown-black semisolid 2.93 57.4 0.67 33.3

nol in benzene. musty odor, brown fluorescence Total 109.3 90.5 1 05.1

v 1 Where fluorescence is referred to here and in the othcr t:.. 1;, fluorescence in ultraviolet light is meant.

From the results recorded in Table l, it-can be seen percentot the'total sulfur in the charge oil. As Table that our process using an alumina adsorbent produced ll, shows, the third fraction was richin nitrogen, containa first fraction comprising 44.6 weight percent of the m 3,3 weight percent i Y I Y crude shale'oil which was colorless, nitrogen-free and ol i A E Hi very low sulfur content. The other two fractions obtained were rich in sulfur and nitrogen compounds and would be sources of valuable chemical compounds.

The shale oil ofExample l diluted with about twice its volume of cyclohexane was fractionated according to the procedure of Example I but. using four eluant liquids, namely, n-pentane, cyclohexane, carbon tetrachloride, and

EXAMPLE ll a solution of volume percent ethanol in benzene. The

The shale oil of Example I diluted with an equal volume charge oil penetrated about of the column before; of cyclohexane was fractionated according to the proceelution was begun. The results of the fractionatiouare dure of Example l but using as the second stage eluant a given in Table Ill.

' Table '111 Wt. N Percent Fraction 1 Eluant I Description Percent Percent of Trotal 1 .Q. n-Pentane. Colorless oil, plcasantodor, blue fluores- 45.2 0.02 0.5 I

cence. V v I p 2 Cyclohexon... Yellowoil,pleasantodor,bluefiuoresccnce; 4.1 0.00 0.00 3 Carbontetraeh ride Brown-black semisolid, charred odor, no 23.3 2.17 -20.8

fluorescence. l 25 Vol. percent ctha- Brown-black semisolid, rnu'sty' odor, 61.5 3114 58x2" noliu benzene. brown fluorescence. v

Totalfin 105.2 88.5

mixture of 5 volume percent ethanol in pentane. The results of the fractionation are recorded in Table H below.

Table II 1 Wt. N, Per- Percent S, Per- Percent Fraction Eluant Description Percent cent of dilotal cent of Tsotal 1 n-Pentane Yellow tint in colorless 43.1 0.00 0.00 0.19 12.2

thixotropic oil, pleasant odor, blue fluorescence.

2. 5Vol. percent ethanol Brown-black semisolid, 54.3 2.4 '76.? 0.95 77.0'

I inpentane. musty odor, br0w11.flu-, V I

OT'QSCQHCB. 3;. 25V01.percentcthauol Brown-black solid phe- 8.8 3.3 17.1 0.82 10.8

inhenzeue. nolic odor, no uoresv (361109. Total 106.2 93.8 100.0

Thefirst fraction obtained in Example ii is seen to be Table lII'shows that the first fraction obtained in Exvery similar to the first fraction of Example I. This ample Ill was'comparaole to the first fractions of Ex- Would be expected since the adsorbents, the charge and amples l and H. The second fraction which was eluted the first eluants for the two examples were the same. with cyclohexane demonstratesthe slightly greater elutive However, the second fraction of Example ll was conpower of the cyclic paraffin eluant as compared with siderably larger than the second fraction of Example 1 n-pentane. The cyclohexane'removed a fraction comprisand this was due to the fact that the second eluantof ing 4.1 weight percent of the charge. The carbon tetra- Exarrrple ll comprising a mixture of 5 volume percent chloride used as the eluant for the third stage produced ethanol in pentane was stronger than the benzene used a fraction rich in nitrogen. The fourth eluant comprisas the second eluant in Example I. This illustrates a point g 25 Volume Pfl lw 1 nz n produced, a fracwhich we have discussed, namely, that mixing even a small tiOn which was also rich in nitrogen. amount of a strong eluant (ethanol) with a weak eluant I (pentane) produces a mixture having rather strong elutive 1 IV power. The second fraction contained 76.7 weight per: The shale oil of Example I dilutedwith an equal volcent of the total nitrogen in the charge oil and 77.0 weight time of cyclohexane was fractionated according to the procedurelo f Example L'but using carbon tetrachloride as the second eluant. The results of the fractionation are given in Table IV.

benzene was rich injnitrogen and contained 84.9" percent of the nitrogen present in the charge oil;

Table IV Wt. N, Per- Percent S, Per- Percent Fraction Eluant Description Percent cent of 'Igtal cent of 'lotal 1 Oyelohexane Brown-black thixotropie 43.5 0.08 2.1 0.38 24.7

011, pleasant odor, no fluorescence. 2 Carbontetrachloride... Brown-black semi-solid, 28.1 2.29 37.6 1.04 43.0

musty odor, no fluores- (381109. 3 25 VolPercentethanol Brown-black semi-solid, 31.5 3. 31 61.4 0.68 32.0

in benezene. mustyodonbrownfluorescenee.

TotaL. 103.1 101.1 100.3

In Example lV cyclohexane was used as the first eluant EXAMPLE VI and produced a fraction comparable in an amount to the The Shale oil f Example I diluted with about twice first fractions of Examples I, II and III but the cyclohexane eluate was dark in color. However, despite the dark color, the cyclohexane fraction had a low nitrogen its volume of cyclohexaue was fractionated in the bauxite. column as in Example V but using benzene as the second stage eluant. The results of the fractionation are content and a much lower sulfur content than the charge given in Table VI.

Table VI Wt. N, Per- Percent S, Pcr- Percent Fraction Eluant Description Percent cent of 'Igotal cent of Total l S 1 n-Pentane Colorless thlxotropie oil, 38.4 0.00 0 .0 0.06 3.4

pleasant odor, non-fluorescent. t 2 Benzene Brown-black semisolid, 22.5 1.09 14.4 1. 44 48.4

musty odor non-fluorescen 3 Vol. percent etha- Brown-black semisolid, 41.8 3.27 80.5 0.52 32.4

nol in benzene. musty odor, brown tluorescence.

Total 102. 7 94. 9 84. 2

oil. The second and third fractions were rich in sulfur and nitrogen compounds.

EXAMPLE V The shale oil of Example I diluted with about twice its volume of cyclohexane was introduced at the top of a column of 100 mesh activated bauxite known commercially as Regular Iron Porocel. The adsorbent column was 2 feet in length and contained ml. of adsorbent. The column was eluted successively with 130 ml. portions of cyclohexane, carbon tetrachloride and a mixture of 25 volume percent ethanol in benzene. The results of the fractionation are given in Table V.

Table VI shows the results obtainable with a bauxite adsorbent and the same eluants employed in Example I but diluting the shale oil charge with about twice its volume of cyclohexane. The n-pentane first fraction was free of nitrogen and substantially free of sulfur. It was a colorless oil comprising 38.4 weight percent of the crude shale oil charge. The benzene fraction had a high sulfur content and a rather high nitrogen content. The third fraction eluted with a mixture of ethanol and benzene had a very high nitrogen content and contained 80.5 percent of the nitrogen present in the crude shale oil.

From the tables above it can be seen that in each of the examples a total crude shale oil of high nitrogen Table V Wt. N, Per- Percent S, Per- Percent Fraction Eluant Description Percent cent of 'lllotal cent of 'lotal I Cyclohexanc Colorless oil, pleasant 38.0 0.00 0.00 0. 47 26.7

odor, light blue fluoreseence. 2 Oarbontetrnchlorlde... Brown-black semisolid, 16.0 1.30 12.2 1.37 32.7

musty odor, nonfluorescent. 3 25 Vol. Percent etha- Brown-black semisolid, 49.9 2.89 84.9 0.79 58.8

n01 in benzene. musty odor, brown fluorescenee.

Total 103.9 97.1 118.2

The results of Example V show that the use of bauxite as the adsorbent and cyclohexane as the first eluant liquid produced a large colorless first fraction. This fraction comprised about 38 percent of the crude shale oil and was free of nitrogen and lower in sulfur than the charge. The fraction eluted with carbon tetrachloride had a high nitrogen and sulfur content. The third fraction which was eluted with a mixture of 25 volume percent ethanol in and sulfur content which was only moderately diluted was fractionated and a fraction was recovered which was completely or substantially free of nitrogen as indicated by a Kjeldhal nitrogen analysis. free fraction recovered by n-pentane comprised as much. as 45.2 percent by weight of the crude shale oil charge. This fraction was also of low sulfur content, having a. sulfur content as low as 0.06 percent by weight in the frac- The nitrogenelution, the fractionations of the examples also produced" fractions of high nitrogen and sulfur content. Thus, the third fraction of Example. IV contained 3.31 percent by weight of nitrogen. Apparently, this fraction consisted substantially entirely of nitrogen and sulfur compounds and would be a source for valuable chemical compounds.

Obviously many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof and therefore only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. A process for separating from a shale oil containing substantialamounts of sulfur and nitrogen compounds a fraction of reduced nitrogen and sulfur content, which comprises introducing a liquid comprising at least about 25 volume percent of said shale oil into. contact with a bed of adsorbent material selected from the group consisting of activated alumina and activated bauxite in an amount which penetrates no more than about 90 percent of the length of the adsorbent bed, thereafter eluting said adsorbent bed with a non-polar eluant, and recovering eluate of low sulfur and low nitrogen content from the absorbent bed.

2. A process as set forth in claim 1 in which the ad sorbent bed is 'wetted with eluant prior to the introduction thereto of the liquid to be fractionated.

3. A process for separating nitrogen and sulfur compounds of a shale oil from the hydrocarbons of said shale oil which comprises introducing a liquid comprising at least about 25 volume percent of said shale oil into contact with a bed of adsorbent material selected from the group consisting of activated alumina and activated bauxite in an amount which penetrates no more than about 90 percent of the adsorbent bed, thereafter contacting said adsorbent bed with a series of eluant liquids of successively stronger eluting powers and recovering separately each eluate as elutedfrom the bed. 7

4. A process for separating nitrogen and sulfur compounds of a total crude shale oil from the hydrocarbons of said shale oil which comprises introducing a liquid comprising at least about 25 volume percent of said total crude. shale-oil -into contact with a'bed ofadsorbentma-v terial selected from the group consisting of activated alumina and activated bauxite in an amount which penetrates no more than about 90 percent of the adsorbent bed, thereaftercontacting said adsorbent bed with a series of eluant liquids of "successively stronger eluting powersand recovering separately each eluate as eluted from the bed.

5. A processfo'r separating nitrogen and sulfurconr pounds ofashale oil from thehydrocarbons of said shale oil which comprises introducing a liquid comprising at least about 25 volume percent shale oil into contact with a bed of adsorbent material selected from the group consisting of activated alumina and activated bauxite in an amount which penetrates no more than about 90 percent.

of the adsorbent bed, thereafter contacting said adsorbent bed with a wholly paratfinic eluant liquid, recovering from the bed a first eluate comprising a substantially colorless oil which is substantially free of nitrogen and low in sulfur, thereafter contacting said adsorbent bed with a series of eluant liquids of successively stronger eluting powers and recovering separately each eluate as eluted from the bed.

6. A process for separating nitrogen and sulfur com pounds of a shale oil from the hydrocarbons of said shale oil which comprises introducing a liquid comprising at least about 25 volume percent of said shale oil into con tact with a bed of adsorbent material selected from the group consisting of activated alumina and activated bauxite in an amount which penetrates no more than about 90 percent of the adsorbent bed, thereafter contacting said adsorbent bed with a series of eluant liquids of successively stronger eluting powers, recovering separately each eluate as eluted from the bed and collecting at least one of said eluates in more than two portions by making successive cuts in the emerging eluate.

References Cited in the file of this patent UNITED STATES PATENTS 2,390,917 Breth et a1 Dec. 11, 1945 2,398,101 Lipkin Apr. 9, 1946 2,606,143 Smith et a1. Aug. 5, 1952 2,621,203 Cope Dec. 9, 1952 2,651,594 Blatz Sept. 8, 1953 OTHER REFERENCES Cassidy: Adsorption and Chromatography, Intersciencef Publishers Inc., New York (1951), page 232. 

1. A PROCESS FOR SEPATATING FROM A SHALE OIL CONTAINING SUBSTANTIAL AMOUNTS OF SULFUR AND NITROGEN COMPOUNDS A FRACTION OF REDUCED NITROGEN AND SULFUR CONTENT, WHICH COMPRISES INTRODUCING A LIQUID COMPRISING AT LEAST ABOUT 25 VOLUME PERCENT OF SAID SHALE OIL INTO CONTACT WITH A BED OF ADSORBENT MATERIAL SELECTED FROM THE GROUP CONSISTING OF ACTIVATED ALUMINA AND ACTIVATED BAUXITE IN AN AMOUNT WHICH PENETRATES NO MORE THAN ABOUT 90 PERCENT OF THE LENGHT OF THE ADSORBENT BED, THEREAFTER ELUTING SAID ADSORBENT BED WITH A NON-POLAR ELUANT, AND RECOVERING ELUATE OF LOW SULFUR AND LOW NITROGEN CONTENT FROM THE ABSORBENT BED. 